Hand-operated tube-bending machine



March 6, 1962 G- A. SALL HAND-OPERATED TUBE-BENDING MACHINE Filed Feb.1, 1960 United States Patent 3,023,650 HAND-OPERATED TUBE-BENDINGMACHINE Gustav A. 82111, 1794 20th St., Rockford, Ill., assignor ofone-half to Marie C. Sterner Filed Feb. 1, 1960, Ser. No. 5,925 6Claims. (Cl. 81-15) This invention relates to a hand bending machine andparticularly to a machine for bending conduit and the like.

An important object of this invention is to provide a hand bendingmachine which will rapidly and accurately produce an ofiset or reversebend in a section of conduit.

Another object of this invention is to provide a hand bending machinehaving a lever operated eccentric cam for moving one die block towardand away from the other die block and having an improved arrangement formounting the cam lever so as to minimize wear and frictional resistanceto movement of the cam lever between its release and clamping positions.

A more particular object of this invention is to provide a hand bendingmachine having a lever operated eccentric cam for moving one die blocktoward and away from the other, in which the lever operated cam ismounted by links on one die block so as to permit the pivot point of theeccentric cam to shift longitudinally of the other die block as thelever is moved between its clamping and release positions.

Yet another object of this invention is to provide a hand bendingmachine which is of simple construction and which can be easily andeconomically manufactured.

These, together with various ancillary objects and advantages of thisinvention will be more readily appreciated as the same becomes betterunderstood by reference to the following detailed description when takenin connection with the accompanying drawings wherein:

FIGURE 1 is a perspective view of the hand bending machine;

FIG. 2 is a sectional view through the bending machine taken on theplane 22 of FIGURE 1 and show ing the lever in its release position;

FIG. 3 is a longitudinal sectional view taken on the plane 3-3 of FIGURE1 and showing the lever in its clamp position; and

FIG. 4 is a transverse sectional view taken on the plane 4-4 of FIG. 2.

In electrical outlet and junction boxes, the side openings in the boxesare offset from the rear face of the box and when installing theconduit, it is frequently necessary to provide an oifset or reverse bendin the end of the conduit such that the conduit will extend flush alongthe supporting surface when the olfset end is inserted into a sideopening in the box. At present these offsets or reverse bends of theconduit are made in two separate bending operations and considerableskill is required to provide two equal but oppositely facing bends ofproper magnitude and at the proper distance apart to achieve the desiredoffset. Even with skilled operators the bends initially made in theconduit do not always accurately produce the desired offset and it isfrequently necessary to partially straighten or rebend the initial bendsin the conduit to correct the offset. This is time Patented Mar. 6, 1962consuming and, moreover, does not produce the uniformly consistentoffsets necessary to a neat appearing installation.

The hand bending machine of the present invention is arranged to producea preselected offset or reverse bend at any desired point in a conduitand includes upper and lower die blocks 10 and 11 and a cam opera-tinglever 12 for selectively moving the die blocks toward each other to bendan oifset in a conduit. The die blocks 10 and 11 are guidably mounted oneach other by means of pins 14 and 15 which are threadedly mounted inopenings 16 and 17 in the upper and lower die blocks, respectively, andat diagonally opposite corners thereof. The pins are guidably receivedin bores 18 and 19 in the lower and upper die blocks respectively andsprings 21 are preferably disposed in the bores 18 and 19 to engage theguide pins and yieldably urge the die blocks apart. Additional springssuch as 22 are disposed in registering bores 23 and 24 in the die blocks10 and 11, at the corners opposite the guide pins 14 and 15. As isapparent, the springs 21 and 22 yieldably urge the die blocks 10 and 11apart, to the position shown in FIGS. 2 and 4.

The lower die block 11 has an upper face formed with relatively parallelend portions 31a and 3117 which are offset from each other and areconnected by a reverse bend portion 310 that merges smoothly with theend portions. The upper die block 16 is formed with a lower facecomplementary to the upper face of the lower block and having relativelyparallel end portions 32a and 32b connected by a reverse bend portion32c. The off-set between the end portions of the registering faces ofthe die blocks is made equal to the offset desired to be produced in theconduit. Complementary grooves 33 and 34, each having a semi-circularcross-section are formed in the registering faces of the die blocks and,when the die blocks are closed, define an oifset passage for receivingand shaping the conduit 36. In the specific embodiment illustrated, thedevice is arranged to bend half-inch conduit and produces a one-halfinch offset in the conduit, it being understood that diiferent dieblocks or at least different die faces would be used for different sizeconduit or pipe. As will be noted, the sides of the grooves 33 and 34serve to confine the conduit 36 therebetween and thus inhibit andeffectively prevent lateral spreading or flattening of the conduitduring the bending operation. As a result, the offset bend in theconduit 36 retains the circular configuration of the conduit and doesnot materially inhibit the passage of the electrical conductors throughthe conduit.

The lever 12 has a pin 41 extending therethrough defining a pivot axisfor the lever, and a nose portion 42 which is eccentric to the pin 41and arranged to engage the upper die block 10. In accordance with thepresent invention, the lever is mounted so that the nose portion maymove along the upper die block as the lever is moved from its raisedposition shown in FIG. 2 to its lowered position shown in FIG' 3, tominimize wear and frictional resistance to turning of the cam lever. Forthis purpose, links 44 and 45 are pivotally mounted by a pin 46 on thelower die block 11, and the upper pin 41 extends through the links tosupport the cam lever on the upper end thereof. Thus, the pivot axis ofthe lever .is free to shift in a direction longitudinally of the upperblock, as the lever 12 is raised and lowered. In order to inhibitrelative sliding between the eccentric nose portion 42 and the upper dieblock lit, the nose portion 42 has transversely extending teeth .8 whichform an eccentric sector-type gear adapted to mesh with rack teeth 49formed on the upper die block 10. The springs 21 and 22 urge the upperdie block upwardly and press the upper die block against the eccentricnose portion 42 of the lever so that the lever normally remains in anupright position. Stop dogs 51 are provided adjacent the end of the rackteeth 49 on the upper die block to prevent the cam lever from movingpast an overcenter position.

The bending tool is advantageously arranged so as to facilitate castingof the rack teeth 48 and 49 on the lever 12 and upper die block ltlrespectively. As best shown in FIG. 4, the rack teeth 48 on the leverhave a slight taper or draw essential to enable removal of the molds,and the rack teeth 49 on the upper die block similarly have an outwardtaper or draw. In order to improve the contact between the sector teeth43 and the rack teeth 49, the rack teeth have a longitudinal groove orslot 52 milled or cut therein so as to separate the rack teeth intospaced rows of teeth.

From the foregoing it is thought that the operation and construction ofthe hand bending device will be readily understood; The links 44 and 45extend alongside the upper and lower die blocks it? and 11 and aid inguiding the die blocks into and out of registry with each other. Whenthe lever 12 is in its raised position, the springs 21 and 22 open thedie blocks and permit a straight section of the conduit to be insertedinto the registering grooves 33 and 34 in the die blocks. As the leveris moved downwardly, in a counterclockwise direction as viewed in FIGS.2 and 3, the eccentric nose 42 on the lever presses the upper die blockdownwardly toward the lower die block. The links 44 and 45 permit thepivot pin 41 and hence the pivot axis of the lever 12 to shiftlongitudinally of the upper die block so that there is no relativesliding between the eccentric nose and the upper die block duringoperation of the bending machine. This is advantageous in that iteliminates the friction and wear between the nose portion and the upperdie block. It will additionally be noted that this arrangement is suchthat the point along the upper die block, at which pressure is appliedby the eccentric nose portion, will shift along the upper die block asthe lever is moved toward its lower position so as to apply pressurealong the upper die block in a progressive fashion.

The pivot point of the lower end of the links 44 and 45 on the pin 46 ispreferably located at a point intermediate the ends of the reverse curveon the lower die block and, preferably such that the links will move toan overcenter position such as shown in FIGS. 1 and 3 when the lever isin its lower position. ment, the eccentric nose portion is operative topress the upper die block it downwardlyand in a direction to the rightas viewed in FIG. 3 to oppose the endwise pressure exerted on the upperdie block by the conduit 36 during bending of the ofiset.

Since the offset in the conduit is bent in a single operation, theoffset can be rapidly formed and the amount and position of the offsetaccurately controlled to produce uniform results. Moreover, the sides ofthe shaping grooves 33 and 34 in the die blocks confine the tube so asto prevent lateral spreading or flattening of the tube.

I claim:

1. A hand conduit bending machine comprising first and second elongatedblocks mounted in side-by-side relation for movement toward and awayfrom each other and having longitudinally extending undulated channelsin the registering side faces thereof for receiving and shaping aconduit section, a link pivotally mounted on said first block andextending alongside said second block for With this arrangemovement in aplane disposed longitudinally of said second block, a lever pivotallymounted on the end of said link remote from said first block and havinga nose portion eccentric to its pivot axis on said link and engageablewith said second block for moving the second block toward the firstblock, means on said nose portion and the side of said second blockengaged by the nose portion for preventing sliding movement therebetweenas the lever is pivoted relative to said link, said link pivotingrelative to said first block as the lever is pivoted relative to thelink whereby the point of contact between the nose portion and thesecond block shifts along the second block.

2. The combination of claim 1 wherein said means for preventing slidingmovement includes rack teeth formed on said block and intermeshing teethon the eccentric nose portion of the lever.

3. The combination of claim 1 wherein said means for preventing slidingmovement includes spaced rows of rack teeth on said second block andintermeshing teeth on the eccentric nose portion of the lever.

4. A hand bending machine for producing ofiset bends in conduitcomprising, upper and lower elongated blocks mounted for movement towardand away from each other, said lower block including an upper facehaving relatively parallel end portions oifset from each other andconnected by a reverse curve portion merging with the end portions, saidupper block having a lower face complementary to said upper face on thelower block and adapted to register therewith, the registering faces onsaid upper and lower blocks having opposed channels therein forreceiving a section of conduit, 2. link pivotally mounted on the lowerblock intermediate the ends of the reverse curve portion for movementrelative to the lower block in an upright plane, and a lever pivotallymounted on the upper end of the link and having a nose portion eccentricto its pivot axis for urging the upper block toward the lower block.

5. A hand bending machine for producing offset bends in conduitcomprising, upper and lower elongated blocks mounted for movement towardand away from each other, said lower block including an upper facehaving relatively parallel end portions ofifset from each other andconnected by a reverse curve portion merging with the end portions, saidupper block having a lower face complementary to said upper face on thelower block and adapted to register therewith, the registering faces onsaid upper and lower blocks having opposed channels therein forreceiving a section of conduit, a link pivotally mounted on the lowerblock intermediate the ends of the reverse curve portion for movementrelative to the lower block in an upright plane, a lever pivotallymounted on the upper end of the link and having a nose portion eccentricto its pivot axis for urging the upper block toward the lower block, andinterengaging teeth formed on said upper block and on said nose portionto inhibit sliding movement between the lever and the upper block in adirection longitudinally of the upper block.

6. A hand conduit bending machine comprising first and second elongatedblocks disposed in side-by-sid'e relation and having longitudinallyextending 'undulated channels in the registering side faces thereof forreceiving and shaping a conduit section, said blocks having slidablyinterfitting pins and sockets on the registering faces thereof adjacenteach end of the blocks and at opposite sides of the channels thereinsupporting the blocks for movement toward and away from each other, alink pivotally mounted on said first block and extending alongside saidsecond block for movement in a plane disposed longitudinally of saidsecond block, a lever pivotally mounted on the end of said link remotefrom said first block and having a nose portion eccentric to its pivotaxis on said link and engageable with said second block for moving thesecond block toward the first block, means on said nose portion and theside of said second block engaged by said nose portion for preventingsliding movement therebetween as the lever is pivoted relative to saidlink, said link pivoting relative to said first block as the lever ispivoted relative to the link whereby the point of contact between thenose portion of the lever and the second block shifts longitudinally ofthe second block.

1,321,663 Osborne Nov. 11, 1919 Durner Feb. 15, 1921 Cronwall July 23,1929 Harvey Sept. 16, 1930 Dale Oct. 5, 1937 Pimentel July 31, 1945James Feb. 1, 1955 FOREIGN PATENTS Switzerland Jan. 16, 1933 BelgiumJan. 15, 1957 Germany Aug. 7, 1928

